Differential cylinder with toggle lock



r Nov. 17; 1953 E D N 2,659,207

' DIFFERENTIAL CYLINDER WITH TOGGLE LOCK Filed Dec. 26. 1952 INVENTOR.

Mmym ATTORNEYS.

Patented Nov. 17, 1953 DIFFERENTIAL CYLINDER WITH TOGGLE LOCK George B. Marsdcn, Cicero, Ill., assignor to Chicago Nipple Manufacturing Company, a corporation of Delaware Application December 26, 1952, Serial No. 328,017 8 Claims. (01. 60-97) This invention relates to a differential cylinder with a toggle lock and more particularly to a fluid operated cylinder and piston device emp ying a toggle linkage to connect the pistons during certain stages of operation.

- Differential cylinder mechanisms have heretofore been proposed in which the operating fluid is-first effective on a relatively small pistonand thereafter on a larger piston which is releasably connected to the small piston. One such mechanism is more particularly disclosed and claimed in my copending application, Serial No. 337,157, filed February 16. 1953. The present invention relates to a differential cylinder mechanism of this type and has'for one of its objects the pro-- vision of a simplerndefiective mechanical looking means to connect the pistons.

Another object is to provide a differential cylinder in which the pistons are connected through a mechanical'linkage which is extended by movement of the small piston relative to the large piston and which is locked in its extended position by initial movement of the large piston.-

Still another object is to provide a differential cylinder in which the linkage is held extended by a stationary cam surface engaging aportion of the linkage after it is initially moved by the large piston. A further object is-to provide a differential cylinder in which'the pistons are returned to their initial position by-means acting-- solelyon the small piston. In this construction the linkage Figure l is a longitudinal central sectionwith parts'in elevationthrough a difierentialcylin'der embodying the invention; v I Figure 2 is a view-similar to Figure 1 sho ing the parts in a moved position; and- Figure 3 is a transverse section on the 3--3oiFigure 1. The cylinder construction as showncomprises a' body 'or housing "I which may be inthe form.

of an integral casting andwhichis formed with a first relatively large-bore I I and a'second smaller bore I2 aligned withthebore I I; .The end ofthe line piston I! is formed with a central opening therein through which a smaller second piston I9 projects to fit slidably in the smaller bore I2. The second piston I9 is formed with an extension 2| projecting through the end of the extension I4 to be connected to a load. An annular sealing ring 22 fitted within the extension M seals against the extension 2I to prevent leakage of fluid therebetween.

The extension 2| is formed with an ennular piston 23 which fits slidably in the tubular extension I4 and may be sealed therein by annular sealing means such as an O ring 24. The piston 23 eiiects the return stroke of cylinder. The pistons I! and I9 are connected by a toggle linkage including a first link 25 pivoted at one end' to the extension '2I and a second link 26 pivoted at one end to ears 2'! carried by'the piston l1.- At their opposite ends the toggle links are connected by pivot pins 28 which project outward therefrom to fit-into cam tracks provided in the sides ofthe -body.

As best seen in Figure throughout a portion thereof :to form flat parallel surfaces at its sides in which the cam tracks may be cut. As shown, the togglelinkage is duplicated with similar single togglelinks at each side-of the extension 2i so that pins 28 extend outwardly from each side of the pistons. part of the housing, as shown at 29,- ,provides fiat surfacesgenerally parallel to the planes of the single linkages which are cut out through a V relatively large rectangular area3l and through relatively narrow forwardly exi iending grooves 32 I defining the cam tracks.

V l When the mechanism is inits initialgpositionth f e on ar move q h t as shown in Figure l,- and thef'toggle linkages are collapsed so that the pivot pins 28 thereoflie in; the upper [lefthand portions of the c am tracks 3| When operating ;fiuid is supplied through the connection I5, it will act on the exposed end of the'small second piston I9 to move; it to the right. 'At this time thepiston ll will, remain stationary since the operatingfluid does not act on it. J' -Ihis phase 7 of operation continues until the small. piston has moved out of the bore l2 to expose the large 3, the body iis enlarged The enlarged slots 32. right, however, the toggle linkage is held extended ton i! has been moved, the toggle linkage will be substantially straightened out to the position shown in Figure 2 and the pins 28 wiillbedirectly in front of the slots 32 andbreak close to theentrances thereof. Upon initial movement of the piston H, the entire toggleliniiage will be shifted bodily to the right to move the pins 28 into the slots 32 which act as fixed cam surfaces to hold the toggle linkage in its extended position. It will be noted that. the toggle; linkage is never completely straightened out soxthazt when the force is exerted; on: the right end thereof in compression, it will collapse to:- the position shown. in Figure 1 after the pins 28 have. moyedi outofi the During continued movement to the by the; camming efiectof the slots 32 so that the extension 21 and the; load will be moved by: the

large: piston at a relatively low rate and with. a

high degree of 'force.

To return the parts to their initial position pressure on the. connection i5 is relieved and operating fluid under pressure. is supplied to the connectionpressure acts on the right end of the annular piston 23 to'urge the connection 2! and the small piston to the left. As long as the pins 28 remain in the slots 32-, the toggle linkage cannot buckle so that the large piston be moved back to the left to its initial position as shown in Figure. 1 through the toggle linkage. As soon as the pins remove out of the. slots 3?, the toggle linkage. will buckle due. to. the coni amessive force thereon allowing the. small. pistoni -l lito move to the left relative to the piston n. This movement will continue until; the parts the position shown in Figure l which constitutes their extreme lefthand position after which they are ready for a succeeding: operation.

smaller diameter aligned with the first bore; a

first piston slidablein the first bore a second piston sl-idahlein the second bore and having anextension projecting slidabl-y'through the first pi-s- Etdn and adapted to beconnected to a load, a connee'tion to supply operating fluid to the second bore-at the end thereof remote from the first here to urge the second piston toward the first bore, the secondpiston moving-out of the second bore to open the first ligore to the connection whereby the firs'tpis'ton will bemoved, an extensible linkage connected at its "ends to the first piston and the extension to be extended when the second -piston moves relative to the first piston, and hold- 'in'g means cooperating with the linkage and -ma-de effective by initial movement ofthe first 4* piston to hold the linkage in its extended condition.

2. The construction of claim 1 in which the holding means comprises a cam surface fixed with respect to the body and engaging the linkage after initial movement of the first piston to hold the linkagejin extendelipositiom 3-. A differential cylinder comprising a body formed with a first bore and a second bore of smaller diameter aligned with the first bore, a

firstpiston. slidable. in the first bore, a second piston slidable in the second bore and having an extension projecting slidably through the first pis- 4 tonand adaptedto be connected to a load, a

1 connectiomto-supply operating fluid to the second bore at theend thereof remote from the first here to; urge. the, seeond piston toward the first bore, the second piston moving out of the second bore 'to-openthe first bore to the connection whereby the first piston will be moved, a toggle linkage connected at its opposite ends.- to; the first piston and the extension respectively to be extended as: the second piston moves relative. to the first piston, the linkage including an intermediat joint movable laterally of the; pistons as thelinleage is extended, and a cam, surface fi-x-edi with respect to the body to engage said. mtermediate joint; after initial movement of the first. piston to. hold the linkage extended durimgv further movement of the pistons.

4. A. differential cylinder comprising a body formed with a; first bore. and a, secondbore of smaller diameter aligned with, the: first bore, a first piston slidableinthe firstbore, a secondpiston siidable in the second bore and having-an extension projecting sl-idablythrough the first. piston and adapted. to. be connected to; a load, a connection to supply operating fluid. tothesecond bore at the end thereof remote from the first-bore to urge the second piston. toward, the first bore, the: second piston moving out: of the,- secondbone toopen the first bore to the-connection whereby the; first piston will be moved; a toggle linkage including a pair of links having. a common pivot connection at one end and, pivoted at their other ends to the first piston and the extension-x respectively tobe; extended to a substantially straight position as the second piston moves relative tothe first piston, and-a. cam surfacefixed relative to the bodytoengage the. common pivotconnection atter initial movement of the fiagst piston and hold the linkage extended during further movementot the pistons.

5. Adifierential cylinder-comprising a. :body formed with a first bore and-a secondbore of smaller diameter aligned with the first bore, a first piston slidable in the first bore, a second piston slidable in the second bore andhaving an extension projecting .slidably throughthe first piston and adapted to be connected to a load,

I a-eonnection to supply operating fiuid to the second bore at. the end thereot remote from thefirst bore to urge the second piston toward-thefirst bore, the --secon d piston moving out of the secend hereto-open the first bores-tothaconnection whereby the first piston he -moved, an extensible linkage connected alt-its ends; to the r'eiitensi'on or the second. pistcnv to move ,the first and second .pistons in the opposite direction.

6. A differential cylinder comprising a body formed with a first bore anda second bore of smaller diameter aligned with the first bore, a first piston slidable in the first bore, a second piston slidable in the second bore and havin an extension projecting slidably through the first piston and adapted to be connected to a load, a connection to supply operating fiuid to the second bore at the end thereof remote from the first bore to urge the second piston toward the first bore, the second piston moving out of the second bore to open the first bore to the connection whereby the first piston will be moved, an extensible linkage connected at its ends to the first piston and the extension to be extended when the second piston moves relative to the first piston, a cam Surface fixed relative to the body and engaging the linkage after it is moved by initial movement of the first piston to hold the linkage extended, the body being formed with a third core through which the extension projects, an annular piston fitting slidably in the third bore, and a connection to supply fiuid to the third bore at the side of the annular piston remote from the first bore to move the first and second pistons in the opposite direction.

7. A difierential cylinder comprising a body formed with a first bore and a second bore of smaller diameter aligned with the first bore, a first piston slidable in the first bore, a second piston slidable in the second bore and having an extension projecting slidably through the first piston and adapted to be connected to a load, a connection to supply operating fluid to the second bore at the end thereof remote from the first bore to urge the second piston toward the first bore, the second piston moving out of the second bore to open the first bore to the connection whereby the first piston will be moved, a toggle linkage including a pair of links having a common pivot connection at one end and pivoted at their other ends to the first piston and the extension respectively to be extended to a substantially straight position when the second piston moves relative to the first piston,

a cam surface fixed relative to the body to engage the common pivot connection after the linkage has been moved by initial movement of the first piston to hold the linkage in its extended position, and return means acting on the extension to move the pistons in the opposite direction.

8. A differential cylinder comprising a body formed with a first bore and a second bore of smaller diameter aligned with the first bore, a first piston slidab-le in the first bore, a second piston slidable in the second bore and having an extension projecting slidably through the first piston and adapted to be connected to a load, a connection to supply operating fiuid to the second bore at the end thereof remote from the first bore to urge the second piston toward the first bore, the second piston moving out of the second bore to open the first bore to the connection whereby the first piston will be moved, a toggle linkage including a pair of links having a common pivot connection at one end and pivoted at their other ends to the first piston and the extension respectively to be extended to a substantially straight position when the second piston moves relative to the first piston, a cam surface fixed relative to the body to engage the common pivot connection after the linkage has been moved by initial movement-of the first piston to hold the linkage in its extended position, the body being formed with a third bore through which the extension projects, an annular piston on the extension fitting slidably in the third bore, and a connection to supply operating fluid to the third bore at the side of the annular piston remote from the first bore thereby to move the first and second pistons in the opposite direction.

GEORGE B. MARSDEN.

References Cited in the file of this patent UNITED STATES PATENTS Number 

